Preservation of hearing in surgery for acoustic neuromas.

Preservation of hearing was attempted in 161 cases of histologically confirmed acoustic neuroma removed by the senior author between January 1, 1970, and September 30, 1991. There were 136 patients with unilateral tumors; 22 patients had bilateral tumors (neurofibromatosis 2) and underwent a total of 25 procedures. Hearing was initially preserved in 35% of patients with unilateral tumors and in 44% of those with bilateral tumors. Results are reported in terms of pre- and postoperative pure tone average and speech discrimination scores. Surgical access to the tumor was obtained via middle cranial fossa and suboccipital approaches. The latter has been used more often over the past 5 years because of a lower associated incidence of transient facial paresis. Persistent postoperative headaches have been the most common complication following the suboccipital approach. The results of preoperative brain-stem auditory evoked response (BAER) studies were useful in predicting the outcome of hearing preservation attempts. Patients with intact BAER waveform morphology and normal or delayed latencies had a higher probability of hearing preservation in comparison to those with abnormal preoperative BAER morphology.

The surgical treatment of skull-base tumors with intracranial extension.

As a discipline, skull-base surgery via the transtemporal route has matured since 1975. Previously considered unresectable, skull-base tumors with intracranial extension can now be successfully removed by means of modification of contemporary exposures with neurosurgical collaboration. Between September 1970 and February 1986, 126 skull-base tumors have been operated on by The Otology Group, P.C. Of these, 49 had intracranial extension. In this article, techniques for tumor removal and dural defect reconstruction are outlined. A single-staged procedure is advised. The advantages of and exceptions to this format are described. Techniques that will prevent postoperative cerebrospinal fluid leakage are highlighted. Results and complications of this surgical series are discussed, and team aspects of this surgery are emphasized.

Cerebellopontine angle lipomas.

Lipomas of the intracranial vault are uncommon lesions. Rarely, lipomas of the cerebellopontine angle have been identified. The two cases of cerebellopontine angle lipomas reported herein brings the number of recorded cases to 13.

Management of bilateral acoustic tumors.

Bilateral acoustic tumors, often felt to represent a central form of von Recklinghausen's disease, pose a particularly challenging problem to the otologist. This retrospective study reviews the evaluation and surgical results in 15 patients with bilateral acoustic tumors from whom 23 tumors were removed. Early diagnosis can be achieved by clinical awareness of the disease, thorough radiologic evaluation, and appropriate family screening. Total tumor removal with preservation of hearing is usually possible if the lesion is not larger than 1.0 cm. Total removal with hearing preservation is usually not possible if the lesion is larger than 2.0 cm. Hydrocephalus and additional tumors can complicate the overall clinical picture. Guidelines for appropriate management of bilateral acoustic tumors are based on tumor size, hearing sensitivity, and associated intracranial pathology.

Cerebrospinal fluid "leaks" and meningitis following acoustic tumor surgery.

We reviewed 271 intracanalicular and cerebellopontine angle lesions removed over the past ten years, 237 by the translabyrinthine or combined approach which created a mastoid defect. The patients were divided into three groups with the following results: (1) obliteration of the mastoid defect combined with older wound closure techniques in the first 188 patients produced CSF leakage in 25% and meningitis in 16% of cases; (2) not obliterating the defect intentionaly in 16 patients produced CSF leakage in 50% and meningitis in 25% of cases; (3) obliteration of the defect combined with newer packing and closure techniques in the last 33 patients produced CSF leakage and meningitis in only 6% of cases. Four problem areas were identified: the eustachian tube, middle ear, mastoid defect, and postauricular wound. Of these, obliteration of the mastoid defect was most important in minimizing postoperative CSF wound leakage, CSF rhinorrhea, and meningitis.

Glioma of the acoustic nerve.

We report a case of astrocytoma of the acoustic nerve. Most gliomas arise from the brainstem, and seldom originate in the acoustic or other "true" cranial and spinal nerves. Clinical features of this rare acoustic tumor differ from those of brainstem gliomas, but are indistinguishable from typical acoustic neurilemoma. We discuss the diagnosis and histogenesis of glioma arising in the eighth cranial nerve. Demonstration of glial fibrillary acid protein, an antigen specific for astrocytes, is a new method of verifying the diagnosis. Review of the literature indicates that a few cases of epithelial-like tumors of peripheral nerves may have been of neuroepithelial origin. The evidence, however, generally is not sufficient to exclude the possibility of metastatic neoplasms or other tumors such as malignant schwannoma and melanoma. Most of these putative gliomas contained gland-like tissue, and did not have the morphologic appearance of astrocytoma, as in approximately five reported examples, and in our case.

A one-stage combined approach for the management of large cerebellopontine angle tumors.

This paper reviews 180 cerebellopontine angle lesions in regard to results and complications of the surgical management with special emphasis on the diagnosis, surgical removal, and results in 60 large (4 cm. or greater) tumors of the CPA. The authors conclude that in their experience a one-stage combined translabyrinthine-suboccipital approach, which is explained in detail, is the procedure of choice in dealing with large tumors of the CPA.

Preservation of hearing in tumors of the internal auditory canal and cerebellopontine angle.

One hundred thirty-nine tumor removals are reviewed with special interest in ten attempts to save hearing. Three patients with bilateral tumors had some hearing preserved. One of these individuals had a 1 cm tumor removed and his postoperative SRT and discrimination scores were the same as his preoperative ones. Overall, the authors were able to maintain some hearing in six out of ten attempts. While there is no question that patients with bilateral tumors benefit from residual hearing, this is not always true in unilateral cases. The suboccipital and middle fossa procedures are discussed as well as the relative merits of each approach in the preservation of hearing. The total series (139 tumors) is discussed in detail regarding results and complications.

Compications in acoustic neuroma surgery.

The findings in a series of 80 cerebellopontine angle tumors are presented. Complications and results are covered in detail. A new method of controlling postoperative cerebrospinal fluid (CSF) leak is presented. Care of the eye in postoperative facial paralysis is emphasized, and a new type of moisture chamber is introduced.